Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation And Cash-Based Incentive Compensation (Schedule Of Incentive Compensation Expense) (Details)

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Share-Based Compensation And Cash-Based Incentive Compensation (Schedule Of Incentive Compensation Expense) (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Share-based compensation $ 2,659 $ 1,826
Share-based compensation expense charged to operating income 2,659 1,826
Cash-based incentive compensation charged to operating income 3,778 3,845
Total incentive compensation charged to operating income 6,437 5,671
Parent Company [Member]
    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Share-based compensation 2,659 1,826
Share-based compensation expense charged to operating income 2,659 1,826
Lease Operating Expense [Member]
    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Share-based compensation    116
Share-based compensation expense charged to operating income    116
Cash-based incentive compensation charged to operating income 1,900 1,081
General And Administrative [Member]
    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]    
Share-based compensation 2,659 1,710
Share-based compensation expense charged to operating income 2,659 1,710
Cash-based incentive compensation charged to operating income $ 1,878 $ 2,764